In the petroleum refining industry, heat exchangers of the shell and tube type are commonly used to transfer heat from one fluid to another. Such heat exchangers comprise an outer cylindrical shell and a tube bundle positioned within the shell. The tube bundle comprises a multiplicity of individual tubes retained in position in the bundle by plural tube support plates. In this type of heat exchanger, one fluid is passed through the tubes from one end of the shell to the other and another fluid is passed through the shell around the tubes. In use, the tubes become coated with material due to deposits or corrosive action of the fluid passing over the tube. Such deposits impair the heat transfer capability and restrict the fluid flow around the tube bundle. Accordingly, it becomes necessary periodically to clean the deposits from the exterior walls of the tubes to restore the efficiency of the heat exchanger. Tube bundles in refinery applications are large and heavy; typically, bundles may be in the range of 10 to 30 feet in length and 1 to 3 feet in diameter. Accordingly, it is highly desirable to clean the bundles at the installation site to minimize the handling and transport of the bundles.
In the prior art, apparatus is known for cleaning heat exchanger tube bundles at the installation site. Typical of such prior art is that disclosed in the Nagle U.S. Pat. No. 3,052,245. The apparatus of this patent comprises a power operated roller for supporting the tube bundle for rotational positioning and a beam extending parallel to the rollers for supporting a carriage for a cleaning head. The cleaning head comprises two pairs of nozzles which discharge high velocity, high pressure jets of water against the tubes of the tube bundle. The cleaning head is mounted on slides which are inclined relative to the horizontal and the heads may be adjustably positioned so that the nozzles are properly spaced from the tube bundles in accordance with the bundle size. The carriage is adapted to traverse the beam from one end to the other so that the jets from the nozzles impinge on the tubes throughout the length of the tube bundle in repeated cycles. A similar cleaning apparatus for tube bundles is shown in the Zingg U.S. Pat. No. 3,060,064 and the Shelton et al U.S. Pat. No. 3,225,777. In the Ice U.S. Pat. No. 3,703,905, cleaning apparatus for tube bundles is disclosed with the bundle supported on a pair of dollies with power rollers and a boom extending between the dollies. The boom carries the cleaning head which discharges high pressure water for cleaning the tube bundle. In use, the boom is moved arcuately of the tube bundle and the cleaning head is moved back and forth along the boom.
A general objective of this invention is to provide an improved tube bundle cleaning apparatus and overcome certain disadvantages of the prior art.